down in whorls. Control is suggested when 25 percent of the plants, less than three 

 feet in height, show whorl feeding. 



Granules are preferred, but sprays applied with ground equipment using 10 to 20 gal- 

 lons of water per acre with the spray directed over the whorls will provide fair to 

 good results, depending on the size and location of the worm. For control use 1-1/2 

 pounds of carbaryl (Sevin) or toxaphene. For carbaryl, there is a 21-day waiting peri- 

 od between application and removal of grain, but none for forage. For toxaphene, 

 wait 28 days before removing grain. Do not apply toxaphene more than once after heads 

 start to form. Do not use treated forage for silage. 



Corn leaf aphids may be present in the whorls of sorghum. Research conducted in other 

 states indicates that these aphids seldom affect sorghum production. If the infesta- 

 tion is heavy, malathion will control them. These aphids will suddenly begin to dis- 

 appear just before the sorghum heads. However, it is difficult to sit idly by when 

 aphids are matted on the leaves and the upper leaves are turning brown. 



Lady beetles and their young eat aphids. It takes two to five per plant to make in- 

 roads into the aphid population. As the lady beetles consume the aphids, the beetles 

 will migrate to other crops. This will help control the aphids. 



Greenbugs, a stubby- looking aphid, may be found on sorghum. They can damage sorghum 

 from the seedling up to the early preboot stage, and will often cause the plant to 

 die. As greenbugs suck the plant's sap, they inject a toxin into the leaves that 

 causes a reddish discoloration to develop around the point of feeding. We have not 

 had any reports of greenbug damage to sorghum in Illinois so far. Greenbugs are yel- 

 lowish or bright green, with a reddish tinge on the back of the body. Only the tips 

 of their cornicles and antennae are black. They usually feed on the undersides of 

 the lower leaves. Corn leaf aphids, by contrast, are usually found in the whorls. 

 IVhenever greenbugs are causing the death of more than two normal-sized leaves, they 

 should be controlled. 



The sprays that can be applied by commercial applicators are demeton (Systox) , disul- 

 foton (Di-Syston) , or ethyl parathion. Do not use methyl parathion because of possi- 

 ble injury to some sorghum varieties. The sprays that producers can apply with ground 

 equipmenc are diazinon, dimethoate (Cygon) , or malathion. Allow 28 days to elapse be- 

 tween an application of dimethoate and grain harvest, 35 days for demeton, 7 days for 

 disulfoton, 12 days for parathion, and 7 days for diazinon and malathion. 



Sorg hum midge . Damage to sorghum by this insect has been reported in southern Illinois 

 Injury is caused by tiny maggots feeding inside the seed. If the infestation is severe 

 the heads appear to be blasted or blighted and will produce little or no grain. John- 

 songrass serves as a natural reservoir for infection. 



Damage can only be prevented by controlling the adult midge before the eggs are de- 

 posited. Thus, control requires precise timing of insecticide applications. The adult 

 midge is an orange- colored gnat or fly about 1/12 of an inch long. The flies deposit 

 their eggs in the spikelet or seed husk of the plant, and the orange- colored larvae or 

 maggots live within the developing seeds. 



Late- planted sorghun is usually subject to more damage than plantings made earlier. 

 Because of the critical timing required, chemical control for midge may not be very 

 effective- -particularly where late-planted sorghum shows uneven plant development with 

 head emergence spread over a three- to six-week period. j 



